Who can help with the visual code?

Question

C++ / C#

Good afternoon, comrades,
I'm new to programming and I ran into a problem, I can't compile the code, can you tell me why such errors occur and how to fix it in order to compile the .dll
Actually, here's the code:

#include <stdafx.h>
#include <CRC.h>


DWORD __fastcall ComputeCRC(BYTE* data, int size)
{
  int crc, i;

  crc = 0;

  BYTE* ptr = data;
  int count = size;

  while (--count >= 0)
  {
    crc = crc ^ (int)*ptr++ << 8;
    for (i = 0; i < 8; ++i)
      if (crc & 0x8000)
        crc = crc << 1 ^ 0x10213465;
      else
        crc = crc << 1;
  }
  return (crc & 0xFFFFFFFF);
}

DWORD __fastcall ComputeFileCRC(char* file)
{
  FILE* hFile = fopen(file, "rb");

  if (!hFile)
    return 0;

  fseek(hFile, 0, SEEK_END);
  long size = ftell(hFile);
  fseek(hFile, 0, SEEK_SET);

  BYTE* buff = new BYTE[size];
  fread(buff, 1, size, hFile);

  DWORD crc = ComputeCRC(buff, size);

  fclose(hFile);
  delete [] buff;

  return crc;
}

Here are the shoals:

Thank you in advance for all your help!

Answer 1

Perhaps in CRC.h (or somewhere else) functions are declared to return int, but in the implementation they return DWORD.